Henry a



(No Model.)

, H. A. W. WOOD. METHOD 0]? PREVENTING OFFSET m PRINTING momma.

Patented July 15, 189 0.v

H0., wAsmNavcn n c UNITED STATES PATENT OFFICE.

HENRY A. XVISE \VOOD, OF NEWV YORK, N. Y.

METHOD OF PREVENTING OFFSET IN PRINTING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 432,289, dated July 15,1890.

Application filed December 19, 1889. Serial No. 334,282. (No model.)

To all whom, it may concern.-

Be it known that I, HENRY A. VISE VOOD, of the city of New York, in thecounty and State of New York, have invented a new and useful Method ofPreventing Offset in Printing-Machines, which invention or improvementis fully described and illustrated in the following specification andaccompanying drawing.

The object of this invention is to avail of the principle involved inlithography, which depends upon a dampened surface of the stone or plateto repel the ink from the rollers passing over such stone. To this end atympan-surface for a second impression-cylinder of a perfectingprinting-machineis provided, which is repellent of the ink deposited inprinting the first printed sides of the sheets or web, which ink isbrought into contact with said tympan under pressure in printing thesecond sides. This ink-repulsion avoids the soiling of saidtympan-surface and subsequent reolfset upon the first printed sides ofthe sheets or web.

The accompanying drawing shows a transverse section of so much of arotary printingmachine as is necessary to the illustration of theinvention, and as the constructions of all the parts (therein shown insection merely) are well known in the art, it is not necessary to giveany additional views of them.

In said drawing the several parts are indicated by reference-numbers, asfollows: The number 1 indicates a form-cylinder for the first side; 2,its corresponding impressioncylinder; 4, the form-cylinder for-thesecond side; 3, its corresponding impression-cylinder, and 5 the web ofpaper to be printed on its two sides and thence led, as at 5, to thecutting and delivering mechanism, all of which parts constituteawell-known arrangement in a rotary perfecting-machine. The rollers 6 6are covered with any substance-such as flannel or sponge-suitable to actas a capillary holder of water. The receiving and distributing roller'7, running in contact with the rollers 6 6, is made of wood, metal, orany substance suitable for taking and holding a film of water on itssurface without absorbing the same. The roller 10, of similarconstruction to roller 7, runs with its lower side immersed in water,with which the pan or bowl 9 is partially filled. The ductor-roller 8 iscovered with material for the capillary holding of water, similarly toroller 6. The roller 10 is given a slow continuous rotation, and may beactuated from any moving part of the machine in any of the many ways nowwell known, so as to take up a film of water upon its surface. Theroller 8 is caused to oscillate between contact with roller 10 androller 7, so as to absorb from roller 10 the film of water thereon whilein contact therewith and to impart to roller '7 a similar film, which isin turn absorbed from roller 7 by the rollers 6. In this way, by varyingthe speed of roller 10 and thus the thickness of the film of water takenup by it or the length of time during which the roller 8 remains incontact therewith, or both, the degree of wetting imparted to rollers 66 may be regulated as may be desired, this whole arrangementconstituting what is well known in the art as the damping apparatus, asused on lithographic printing-machines, the rollers 6 6 when so usedimparting dampness to the surface of the stone or printing-plate withwhich they run in contact. In this invention, however, the damping-rollers 6 6 run in contact with the tympan of the secondimpression-cylinder, and the tympan is constructed of any such suitablematerial that water will readily adhere to it without destroying itas,for example, thin rubber or rubber-faced cloth, or paper prepared withany water-proof material which will receive and hold a film of moisture,and thus repel the ink upon the first printed sides of the sheets andprevent its offset from the sheet to said tympan. I do not confinemyself to any specific construction of parts for conveying andregulating a film of water to the said tympan, as this may be done inmany ways which are well known in the art for supplying water or ink toprinting-surfaces; nor do I confine myself to any particular material orpreparation for the ink-repellent tympan of the secondimpression-cylinder. It is well known in the art that oiled orparaffined paper is used as more or less ink-repelling tympans, and thatmeans have been instituted for supplying oil or paraffine or other moreor less oily compounds to the paper tympan of the secondimpression-cylinder of perfecting printing-machines, and I do not claimany such; hut, in contrmlistinetion to all oleaginous substances orcompounds, I use water to make the tympan repellent of the ink.

Ofcoursethetympan,technieallysocalled, furnishes the impression-surfaee,and the impression-surface, whether that of the cylinder itself or ofany imp ressimrcovering, whether technically a tympalrsurface or not, isthe surface to which my invention is applied, and by the term film ofWater I do not confine myself to a visible distinguishable separatesheet of water, but use such term in the sense in which the Waterpresent on the impressionsurface seems to perform its oflice, Whethersuch film be microscopic or hypothetic.

The drawing shows the application of this method to a rotary machineprinting from

